<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script>
        function f() {
            var da = new Date();
            var s = da.getHours();
            var f = da.getMinutes();
            var m = da.getSeconds();
            document.getElementById("sj").innerHTML = s+":"+f+":"+m;
        }
    </script>
</head>
<body onload="setInterval('f()',1000)">
    <p id="sj"></p>
</body>
</html>